Valentin R. Troll, Frances M. Deegan, Thor Thordarson, Ari Tryggvason, Lukáš Krmíček, William M. Moreland, Björn Lund, Ilya N. Bindeman, Ármann Höskuldsson, James M. D. Day
The Reykjanes Peninsula (RP) hosts several volcanic lineaments that have been periodically active over the last 4000 years. Since 2021, following a ca. 800‐year quiescence, eight eruptions have occurred on the RP, with more expected in the future. To better understand the origins of this renewed volcanism and help forecast future eruptions, we examine (i) if the ongoing volcanism is fed from a single or multiple magma storage zone(s) or from several smaller reservoirs and; (ii) where the zone(s) are located (i.e. mantle or lower or upper crustal depths). Using major and trace element geochemistry, oxygen isotopes, and seismic tomography we rule out a single, RP‐scale, deep‐seated magma storage zone. Instead we propose the presence of a ca. 10‐km‐wide region of crustal‐level (9–12 km) magma accumulation beneath the Fagradalsfjall volcanic lineament that fed both the 2021–23 eruptions of the Fagradalsfjall Fires and the 2023–24 eruptions of the Sundhnúkur Fires.
雷克雅未克半岛（RP）上有几条火山线，在过去的 4000 年里，这些火山线周期性地活跃着。自 2021 年以来，经过约 800 年的沉寂，雷克雅未克半岛已发生了八次火山爆发，预计未来还会有更多。为了更好地了解火山活动的起源并帮助预测未来的火山爆发，我们研究了（i）正在进行的火山活动是否来自一个或多个岩浆贮存区，或者来自几个较小的贮存区；（ii）岩浆贮存区的位置（即地幔或地壳下部或上部深度）。利用主要和痕量元素地球化学、氧同位素和地震层析成像技术，我们排除了单一的 RP 规模深层岩浆储集带的可能性。相反，我们认为在法格拉达尔斯菲亚尔火山线下存在一个约10千米宽的地壳级（9-12千米）岩浆积聚区，它为2021-23年法格拉达尔斯菲亚尔火山大火的喷发和2023-24年圣努库尔火山大火的喷发提供了岩浆。
{"title":"The Fagradalsfjall and Sundhnúkur Fires of 2021–2024: A single magma reservoir under the Reykjanes Peninsula, Iceland?","authors":"Valentin R. Troll, Frances M. Deegan, Thor Thordarson, Ari Tryggvason, Lukáš Krmíček, William M. Moreland, Björn Lund, Ilya N. Bindeman, Ármann Höskuldsson, James M. D. Day","doi":"10.1111/ter.12733","DOIUrl":"https://doi.org/10.1111/ter.12733","url":null,"abstract":"The Reykjanes Peninsula (RP) hosts several volcanic lineaments that have been periodically active over the last 4000 years. Since 2021, following a ca. 800‐year quiescence, eight eruptions have occurred on the RP, with more expected in the future. To better understand the origins of this renewed volcanism and help forecast future eruptions, we examine (i) if the ongoing volcanism is fed from a single or multiple magma storage zone(s) or from several smaller reservoirs and; (ii) where the zone(s) are located (i.e. mantle or lower or upper crustal depths). Using major and trace element geochemistry, oxygen isotopes, and seismic tomography we rule out a single, RP‐scale, deep‐seated magma storage zone. Instead we propose the presence of a ca. 10‐km‐wide region of crustal‐level (9–12 km) magma accumulation beneath the Fagradalsfjall volcanic lineament that fed both the 2021–23 eruptions of the Fagradalsfjall Fires and the 2023–24 eruptions of the Sundhnúkur Fires.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"745 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141529694","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We present a 3‐D crustal S‐wave velocity (Vs) model for eastern and northeastern Tibet utilizing ambient noise tomography. Our model reveals that crustal flow channels are absent in northeastern Tibet. In this region, the Kunlun Fault (KLF) significantly impacts mid‐lower crust low‐Vs anomalies. In addition, isolated low‐Vs anomalies beneath the Qilian orogeny are unrelated to the low‐Vs materials of the Tibetan Plateau. In the mid‐lower crust of the Songpan‐Ganzi terrane, its northeastern corner exhibits continuous low‐Vs anomalies, limited to areas south of the West Qinglin and west of 104° E. This suggests that a small‐scale northward viscous flow of crustal materials exists in the eastern KLF. However, two significant crustal flow channels (Vs ≤ 3.3 km/s) are observed in eastern Tibet. The east–west tectonic movements and the obstruction of the Sichuan Basin together facilitate the dispersion of crustal materials southward from eastern Tibet.
我们利用环境噪声层析成像技术，提出了西藏东部和东北部的三维地壳 S 波速度（Vs）模型。我们的模型显示，西藏东北部没有地壳流动通道。在这一地区，昆仑断层（KLF）对中下部地壳低 Vs 异常有很大影响。此外，祁连造山带下的孤立低 Vs 异常与青藏高原的低 Vs 物质无关。在松潘-甘孜地块的中下地壳中，其东北角出现了连续的低Vs异常，仅限于西青林以南和东经104°以西地区。然而，在西藏东部观测到两条明显的地壳流动通道（Vs ≤ 3.3 km/s）。东西向构造运动和四川盆地的阻挡共同促进了地壳物质从西藏东部向南扩散。
{"title":"Ambient noise tomography reveals complex crustal structure beneath eastern and northeastern Tibet: Insight‐ into regional crustal flow","authors":"Tengfei Wu, Chenyang Zou, Yujin Hua, Meng Chen","doi":"10.1111/ter.12736","DOIUrl":"https://doi.org/10.1111/ter.12736","url":null,"abstract":"We present a 3‐D crustal S‐wave velocity (Vs) model for eastern and northeastern Tibet utilizing ambient noise tomography. Our model reveals that crustal flow channels are absent in northeastern Tibet. In this region, the Kunlun Fault (KLF) significantly impacts mid‐lower crust low‐Vs anomalies. In addition, isolated low‐Vs anomalies beneath the Qilian orogeny are unrelated to the low‐Vs materials of the Tibetan Plateau. In the mid‐lower crust of the Songpan‐Ganzi terrane, its northeastern corner exhibits continuous low‐Vs anomalies, limited to areas south of the West Qinglin and west of 104° E. This suggests that a small‐scale northward viscous flow of crustal materials exists in the eastern KLF. However, two significant crustal flow channels (<jats:italic>V</jats:italic>s ≤ 3.3 km/s) are observed in eastern Tibet. The east–west tectonic movements and the obstruction of the Sichuan Basin together facilitate the dispersion of crustal materials southward from eastern Tibet.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"146 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141529695","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jean‐Claude Hippolyte, Paul Mann, Pierre Henry, Abel Guihou, Pierre Deschamps, Camille Ourliac, Nicolas Godeau, Lionnel Marié, Mark B. Gordon
Timing is a key data for understanding the origin of faulting. The Balcones fault system (BFS) extends ~600 km along the northern margin of the Gulf of Mexico oil basin and controls springs that supply the major cities in Texas, but its origin is unclear. We provide its first direct timing by applying U–Pb geochronology on seven calcite‐mineralized fault surfaces. We have found that this extensional fault system formed during the Palaeocene‐middle Eocene time (from 61.3 ± 2.7 to 45.4 ± 2.1 Ma), which is much earlier than previous estimates. We show that the formation of the BFS coincides with the largest clastic influx in the northern Gulf of Mexico basin that resulted from Laramide uplift and erosion. This timing and the location of the BFS along the Ouachita suture, support our interpretation of this fault system formed as the result of lithospheric flexure related to Paleogene sedimentary loading.
{"title":"U–Pb calcite dating reveals the origin of a 600 km‐long intraplate fault: The Balcones Fault System of Texas","authors":"Jean‐Claude Hippolyte, Paul Mann, Pierre Henry, Abel Guihou, Pierre Deschamps, Camille Ourliac, Nicolas Godeau, Lionnel Marié, Mark B. Gordon","doi":"10.1111/ter.12734","DOIUrl":"https://doi.org/10.1111/ter.12734","url":null,"abstract":"Timing is a key data for understanding the origin of faulting. The Balcones fault system (BFS) extends ~600 km along the northern margin of the Gulf of Mexico oil basin and controls springs that supply the major cities in Texas, but its origin is unclear. We provide its first direct timing by applying U–Pb geochronology on seven calcite‐mineralized fault surfaces. We have found that this extensional fault system formed during the Palaeocene‐middle Eocene time (from 61.3 ± 2.7 to 45.4 ± 2.1 Ma), which is much earlier than previous estimates. We show that the formation of the BFS coincides with the largest clastic influx in the northern Gulf of Mexico basin that resulted from Laramide uplift and erosion. This timing and the location of the BFS along the Ouachita suture, support our interpretation of this fault system formed as the result of lithospheric flexure related to Paleogene sedimentary loading.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"347 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141508453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kui Tong, Jinxi Li, Zhiwu Li, I. Tonguç Uysal, Jianxin Zhao, Yuexing Feng, Tian Hua, Shugen Liu
The Dabashan Fold‐and‐Thrust Belt is an important natural laboratory for exploring the Meso‐Cenozoic intracontinental orogenic evolution in China. Due to the severe lack of post‐Early Cretaceous strata, little attention has been paid to Cenozoic tectonic in the Dabashan. This study presents structural analysis, in‐situ U‐Pb dating of calcite in conjunction with petrographic and stable isotopic analyses along the eastern segment of the Chengkou Fault in the Dabashan. Structural analysis coupled with U‐Pb dating of syn‐kinematic calcite slickenfibres suggests two discrete S‐N compressional strike‐slip deformation events associated with localized E‐W extension along the eastern segment of the Chengkou Fault have occurred at the Early Eocene (~57–50 Ma) and Late Oligocene‐Early Miocene (~23–17 Ma), respectively. We tentatively related the Cenozoic deformation events in the study area to the clockwise rotation of the Sichuan Basin, resulting from the combined far‐field stress effects between the India, Eurasia and western Pacific plates.
{"title":"In‐situ U‐Pb dating of calcite slickenfibre constraints on Cenozoic multiple‐phase faulting along the eastern segment of Chengkou Fault, Dabashan Fold‐and‐Thrust Belt","authors":"Kui Tong, Jinxi Li, Zhiwu Li, I. Tonguç Uysal, Jianxin Zhao, Yuexing Feng, Tian Hua, Shugen Liu","doi":"10.1111/ter.12732","DOIUrl":"https://doi.org/10.1111/ter.12732","url":null,"abstract":"The Dabashan Fold‐and‐Thrust Belt is an important natural laboratory for exploring the Meso‐Cenozoic intracontinental orogenic evolution in China. Due to the severe lack of post‐Early Cretaceous strata, little attention has been paid to Cenozoic tectonic in the Dabashan. This study presents structural analysis, in‐situ U‐Pb dating of calcite in conjunction with petrographic and stable isotopic analyses along the eastern segment of the Chengkou Fault in the Dabashan. Structural analysis coupled with U‐Pb dating of syn‐kinematic calcite slickenfibres suggests two discrete S‐N compressional strike‐slip deformation events associated with localized E‐W extension along the eastern segment of the Chengkou Fault have occurred at the Early Eocene (~57–50 Ma) and Late Oligocene‐Early Miocene (~23–17 Ma), respectively. We tentatively related the Cenozoic deformation events in the study area to the clockwise rotation of the Sichuan Basin, resulting from the combined far‐field stress effects between the India, Eurasia and western Pacific plates.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"13 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141192196","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Y. Raghumani Singh, A. Bijayalaxmi Devi, Nithoujam Surdas Singh, Mark B. Abbott, T. Elliot Arnold, W. Ajoykumar Singh, M. Sapana Devi, Sh. Priyokumar Singh, O. Victory Devi
The paper presents a new section of the late Palaeocene‐early Eocene, palynological assemblages and stable carbon isotopes from the Lakadong sandstone member of the East Khasi Hills of Meghalaya (India). The Palaeocene‐Eocene transition (PET) is marked by stratigraphic markers of dinoflagellate cysts (taxa of Apectodinium augustum, now Axiodinium augustum) and negative carbon isotope excursion. The palynofloral assemblage indicates the sequence represents warm, humid tropical to subtropical conditions with heavy rainfall. The depositional environment of the Lakadong Sandstone Member is interpreted to be neritic. The new insights of this study in this section suggest the PET with the occurrence of Apectodinium acme consisting of A. augustum at CS5‐15a.
{"title":"Dinoflagellate cysts from the Shillong Plateau, Meghalaya (India): Palynological signature during the late Palaeocene–early Eocene Transition","authors":"Y. Raghumani Singh, A. Bijayalaxmi Devi, Nithoujam Surdas Singh, Mark B. Abbott, T. Elliot Arnold, W. Ajoykumar Singh, M. Sapana Devi, Sh. Priyokumar Singh, O. Victory Devi","doi":"10.1111/ter.12725","DOIUrl":"https://doi.org/10.1111/ter.12725","url":null,"abstract":"The paper presents a new section of the late Palaeocene‐early Eocene, palynological assemblages and stable carbon isotopes from the Lakadong sandstone member of the East Khasi Hills of Meghalaya (India). The Palaeocene‐Eocene transition (PET) is marked by stratigraphic markers of dinoflagellate cysts (taxa of <jats:italic>Apectodinium augustum</jats:italic>, now <jats:italic>Axiodinium augustum</jats:italic>) and negative carbon isotope excursion. The palynofloral assemblage indicates the sequence represents warm, humid tropical to subtropical conditions with heavy rainfall. The depositional environment of the Lakadong Sandstone Member is interpreted to be neritic. The new insights of this study in this section suggest the PET with the occurrence of <jats:italic>Apectodinium</jats:italic> acme consisting of <jats:italic>A. augustum</jats:italic> at CS5‐15a.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"32 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141150097","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Marcello de Togni, Gianni Balestro, Daniela Rubatto, Daniele Castelli, Marco Gattiglio, Andrea Festa
Paleogeographic reconstructions show that the Ligurian‐Piedmont Ocean (LPO) was a relatively narrow oceanic basin but the actual amount of oceanic lithosphere generated and the timing of magmatic accretion are still subjects of debate. New U–Pb dating of zircon from two pairs of FeTi‐oxide metagabbro and metaplagiogranite s.l. of the Susa and Lanzo Valleys Ophiolites (Western Alps) yields Late Jurassic magmatic ages (~150 Ma), 10–15 Ma younger than most of the magmatism in the LPO. The potential significance of the geochronological data presented are discussed in relation to the structural architecture of the LPO, emphasizing that the investigated ophiolites represent the youngest oceanic lithosphere accreted in the Western Alps.
{"title":"Late Jurassic magmatism in the Ligurian‐Piedmont Ocean constrained by zircon ages of mafic and felsic meta‐intrusives","authors":"Marcello de Togni, Gianni Balestro, Daniela Rubatto, Daniele Castelli, Marco Gattiglio, Andrea Festa","doi":"10.1111/ter.12723","DOIUrl":"https://doi.org/10.1111/ter.12723","url":null,"abstract":"Paleogeographic reconstructions show that the Ligurian‐Piedmont Ocean (LPO) was a relatively narrow oceanic basin but the actual amount of oceanic lithosphere generated and the timing of magmatic accretion are still subjects of debate. New U–Pb dating of zircon from two pairs of FeTi‐oxide metagabbro and metaplagiogranite s.l. of the Susa and Lanzo Valleys Ophiolites (Western Alps) yields Late Jurassic magmatic ages (~150 Ma), 10–15 Ma younger than most of the magmatism in the LPO. The potential significance of the geochronological data presented are discussed in relation to the structural architecture of the LPO, emphasizing that the investigated ophiolites represent the youngest oceanic lithosphere accreted in the Western Alps.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"54 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141058972","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiaochun Wei, Hanlin Chen, Eduardo Garzanti, A. Alexander G. Webb, N. Ryan McKenzie, Ping Wang
Detrital zircon U–Pb geochronology (DZG) is widely used in the provenance analysis and calculating maximum depositional ages (MDAs) of strata. To assess the geologic limitations of this approach, we conducted DZG coupled with bulk‐petrology and heavy‐mineral analyses of Miocene volcaniclastic and non‐volcanic siliciclastic sandstones from the SW Tarim Basin. Although these two sandstone types display greatly different bulk‐petrography and heavy‐mineral signatures, they exhibit similar detrital‐zircon‐age spectra, and thus represent a less common case in which interpretations based on DZG alone may misalign with bulk‐sediment provenance. Most zircon‐based MDAs of volcaniclastic sandstones range from 12.3 to 14.8 Ma, deviating from their ca. 11 Ma true depositional age constrained previously. The similarity of zircon‐age spectra in volcaniclastic and siliciclastic sandstones and the 1–4 M.y. the error of the zircon‐based MDAs is ascribed to the low zircon fertility of coeval alkaline magmatic sources. This study emphasizes the importance of an integrated approach to provenance analysis and chronostratigraphy.
{"title":"Limitations of provenance diagnoses and maximum‐depositional‐age constraints based on detrital‐zircon geochronology: the fertility bias","authors":"Xiaochun Wei, Hanlin Chen, Eduardo Garzanti, A. Alexander G. Webb, N. Ryan McKenzie, Ping Wang","doi":"10.1111/ter.12720","DOIUrl":"https://doi.org/10.1111/ter.12720","url":null,"abstract":"Detrital zircon U–Pb geochronology (DZG) is widely used in the provenance analysis and calculating maximum depositional ages (MDAs) of strata. To assess the geologic limitations of this approach, we conducted DZG coupled with bulk‐petrology and heavy‐mineral analyses of Miocene volcaniclastic and non‐volcanic siliciclastic sandstones from the SW Tarim Basin. Although these two sandstone types display greatly different bulk‐petrography and heavy‐mineral signatures, they exhibit similar detrital‐zircon‐age spectra, and thus represent a less common case in which interpretations based on DZG alone may misalign with bulk‐sediment provenance. Most zircon‐based MDAs of volcaniclastic sandstones range from 12.3 to 14.8 Ma, deviating from their ca. 11 Ma true depositional age constrained previously. The similarity of zircon‐age spectra in volcaniclastic and siliciclastic sandstones and the 1–4 M.y. the error of the zircon‐based MDAs is ascribed to the low zircon fertility of coeval alkaline magmatic sources. This study emphasizes the importance of an integrated approach to provenance analysis and chronostratigraphy.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"253 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141058985","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Early Miocene witnessed major tectonic, palaeoceanographic and climatological reorganizations over the Asian realm. The Himalayan and Tibetan plateau upliftment influenced monsoon intensity during this age. Contemporary high‐resolution tropical hydroclimate records are limited. Here, we present an early Miocene sub‐annual stable isotope record from the growth bands of well‐preserved Turritella sp. from the Kachchh basin, Western India. It showed δ13C and δ18O variabilities from −4.83‰ to −1.80‰ and − 7.06‰ to −2.66‰ (in VPDB) respectively. Conventional oxygen isotope thermometry showed an apparent temperature seasonality from 9.3° to 28.1°C. A comparison of the present early Miocene δ18O record with the modern δ18O records in the carbonates from coastal‐estuarine environments of the Indian Ocean confirmed a high freshwater influx into the NE Arabian Sea during the early Miocene, similar to the modern‐day freshwater plume events observed in the coastal region.
{"title":"Freshwater plume‐like condition near the north‐eastern coastal Arabian Sea during early Miocene: Evidence from the stable isotope record in the growth bands of gastropods (Turritella sp.)","authors":"Yogaraj Banerjee, Prosenjit Ghosh","doi":"10.1111/ter.12719","DOIUrl":"https://doi.org/10.1111/ter.12719","url":null,"abstract":"The Early Miocene witnessed major tectonic, palaeoceanographic and climatological reorganizations over the Asian realm. The Himalayan and Tibetan plateau upliftment influenced monsoon intensity during this age. Contemporary high‐resolution tropical hydroclimate records are limited. Here, we present an early Miocene sub‐annual stable isotope record from the growth bands of well‐preserved <jats:italic>Turritella</jats:italic> sp. from the Kachchh basin, Western India. It showed δ<jats:sup>13</jats:sup>C and δ<jats:sup>18</jats:sup>O variabilities from −4.83‰ to −1.80‰ and − 7.06‰ to −2.66‰ (in VPDB) respectively. Conventional oxygen isotope thermometry showed an apparent temperature seasonality from 9.3° to 28.1°C. A comparison of the present early Miocene δ<jats:sup>18</jats:sup>O record with the modern δ<jats:sup>18</jats:sup>O records in the carbonates from coastal‐estuarine environments of the Indian Ocean confirmed a high freshwater influx into the NE Arabian Sea during the early Miocene, similar to the modern‐day freshwater plume events observed in the coastal region.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"126 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140928563","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Marco Mercuri, Stefano Tavani, Simone Fabbi, Giovanni Lavosi, Eugenio Carminati
The San Potito area in central Apennines (Italy), enclosed within the Latium‐Abruzzi carbonate platform, exposes anomalously pelagic carbonates filling an intraplatform basin formed during Jurassic rifting. Oriented obliquely to the regional NW‐SE trend of Cenozoic thrusts and extensional faults, the basin's eastern boundary fault system, striking N‐S, played a pivotal role in structuring orogenic and post‐orogenic features. Large tracts of the fault experienced double reactivation: positive inversion during Miocene shortening, and negative during post‐orogenic extension. Double reactivation is evidenced by older‐on‐younger extensional contacts, and by the change in orientation of thrusts and recent extensional faults from NW‐SE to NNW‐SSE, the latter being consistent with the trend of Jurassic rift‐related structures of the area. This structural interplay highlights the importance of Jurassic faults and their ability in forcing the structural trends, by surviving across multiple deformation stages, even controlling active extensional seismicity.
{"title":"Long live the fault! Double inversion of a Mesozoic rift‐related fault system in the central Apennines","authors":"Marco Mercuri, Stefano Tavani, Simone Fabbi, Giovanni Lavosi, Eugenio Carminati","doi":"10.1111/ter.12718","DOIUrl":"https://doi.org/10.1111/ter.12718","url":null,"abstract":"The San Potito area in central Apennines (Italy), enclosed within the Latium‐Abruzzi carbonate platform, exposes anomalously pelagic carbonates filling an intraplatform basin formed during Jurassic rifting. Oriented obliquely to the regional NW‐SE trend of Cenozoic thrusts and extensional faults, the basin's eastern boundary fault system, striking N‐S, played a pivotal role in structuring orogenic and post‐orogenic features. Large tracts of the fault experienced double reactivation: positive inversion during Miocene shortening, and negative during post‐orogenic extension. Double reactivation is evidenced by older‐on‐younger extensional contacts, and by the change in orientation of thrusts and recent extensional faults from NW‐SE to NNW‐SSE, the latter being consistent with the trend of Jurassic rift‐related structures of the area. This structural interplay highlights the importance of Jurassic faults and their ability in forcing the structural trends, by surviving across multiple deformation stages, even controlling active extensional seismicity.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"88 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140838218","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Riccardo Vassallo, Joseph Martinod, Sandrine Roy, Christian Sue, Laurent Astrade
The Magallanes–Fagnano Fault is an active strike‐slip structure accommodating the relative displacement between South America and the Scotia Plate. The Chilean portion of the fault is poorly studied because most of it runs below the sea level in the Strait of Magellan. Our tectonic geomorphological study is focused on a rare onshore fault section, along which streams horizontally deflected by hundreds of metres since the last main deglaciation are compatible with a dominant left‐lateral fault kinematics and yield a slip rate of 15.7 ± 2.4 mm/year. This rate is between 2 and 3 times higher than the one estimated on the Argentinian portion of the fault over the same period. This spatial variation may be due to both glacial unloading on the fault zone and/or structural factors. These results point out the need to study strike‐slip faults on several portions to unravel behaviour changes related to internal or external forcing.
{"title":"Along‐strike variation of fault slip rate of a transform plate boundary in Tierra del Fuego (South Patagonia)","authors":"Riccardo Vassallo, Joseph Martinod, Sandrine Roy, Christian Sue, Laurent Astrade","doi":"10.1111/ter.12715","DOIUrl":"https://doi.org/10.1111/ter.12715","url":null,"abstract":"The Magallanes–Fagnano Fault is an active strike‐slip structure accommodating the relative displacement between South America and the Scotia Plate. The Chilean portion of the fault is poorly studied because most of it runs below the sea level in the Strait of Magellan. Our tectonic geomorphological study is focused on a rare onshore fault section, along which streams horizontally deflected by hundreds of metres since the last main deglaciation are compatible with a dominant left‐lateral fault kinematics and yield a slip rate of 15.7 ± 2.4 mm/year. This rate is between 2 and 3 times higher than the one estimated on the Argentinian portion of the fault over the same period. This spatial variation may be due to both glacial unloading on the fault zone and/or structural factors. These results point out the need to study strike‐slip faults on several portions to unravel behaviour changes related to internal or external forcing.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"20 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140576048","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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